The first section of Granito, titled “Chronicle Foretold,” delves into the long-simmering case being built in a Madrid court (the same one that indicted Augusto Pinochet) against two of the generals charged with perpetrating a genocidal campaign against the Mayan people of Guatemala. Estimates have it that 200,000 Mayans were massacred during this war, by a government and military that claimed to be fighting communism, but was also consolidating power. As massive as the damage was, today little evidence of what happened remains: as one interviewee points out, it’s next to impossible to prosecute a human rights case of this magnitude based on personal testimony alone. And so Yates digs up the boxes of long unseen outtakes from Mountains to assist in the prosecution’s case, knowing that one of the defendants happens to have been in it.

Granito weaves together Yates’ involvement with the court case (related in an especially flat voice-over) and two other narrative threads. The first tracks the investigative and forensic work of digging up the remains of the Mayan Disappeared. The second is a more free-floating rumination on Yates’ own naiveté, and how the hopeful scenes that concluded Mountains indicated a more general yearning at the time, when it briefly seemed like a wave of indigenous rebellions could topple U.S.-backed dictatorships across Central America. A former guerrilla leader says ruefully that they couldn’t have anticipated the “uniquely savage counterinsurgency” that wiped whole villages off the face of the earth.

Pondering such monstrous deeds, it can be difficult at times to share Granito‘s faith that bringing any of the murderers to justice can assuage the country’s pain. It’s a slow, years-long crawl to justice. It begins to seem more possible once the film shows an incredible stroke of luck: in 2005, the entire archives of the secret police was discovered by accident. Like their forebears in totalitarian barbarism in the Nazi Party and the Stasi, the Guatemalan secret police kept extensive records of who they disappeared and how.

A paper trail might not be much after 30-odd years of waiting for vindication from forces that have yet to entirely disappear: during the making of this film, one of the forensics workers laboring on a mass grave receives a chilling death threat, likely from a military confederate of one of the generals being investigated). But it’s certainly better than the yawning, mocking question mark of silence that has preceded it.

Now, those disbursing such support have at a very minimum learned to keep their own hands cleaner. As shown in When the Mountains Tremble, the line between the United States funding a government that butchers its people at will and very nearly planning and participating in that butchery was once so blurred as to be almost nonexistent.

When Yates and Newton Thomas Sigel’s film premiered in 1983, the U.S. was in the later stages of a decades-long cooperation with a Guatemalan government that treated its people as little more than chattel to work the great plantations producing fruit for American conglomerates. Earlier attempts to bring the nation out of colonial dependency were met by the U.S.-backed installation of a thuggish dictatorship that terrorized, maimed, and killed. This trigger-happy mentality was particularly vehement when focused on the country’s non-Spanish-speaking Indian population.

At the start of When the Mountains Tremble, Guatemalan activist and Quechua Indian Rigoberta Menchú says it plain: “Our legacy has been pain, suffering, and misery.” Menchú, who won the Nobel Peace Prize 10 years later, serves as the soft-spoken but insistent voice of a film that alternates scenes of heart-stopping beauty with tales of incomparable horror.

Apart from Menchú, this impressionistic film’s tone is hard to get a handle on at first. It shows American involvement in the 1954 overthrow of President Jacobo Arbenz Guzmán in some stiffly recreated scenes between Guatemalan and American officials (using dialogue pulled from declassified documents). Strangely, though, the film does not include anything about the bombing of Guatemala City by the American Air Force, a blatant military intervention.

Once past these rough opening segments, the film hits its stride. With unusual and inspiring bravery, Yates and Sigel go into the most remote villages and venture into the dens of the ruling class. They ride along in trucks and helicopters with government soldiers on raids, embed with the rebels and the villagers who support them. They show the plantations where many thousands of Indians work in servile conditions, rifle-toting guards watching over them as though over prisoners. They interview liberation theologian priests whose view of the word of God doesn’t seem to have anything in common with that of the local archbishop, who mouths oily platitudes from his richly appointed office like a villain in an Alexandre Dumas novel. And they sit down with one General Antonio Maldonado, whose sunglasses, shellacked hair, and air of imperviousness would seem high camp if they didn’t make obvious his barbaric sensibility.

Menchú and others speak vividly of the government’s tactics. Labor organizers and people who have criticized the ruling powers are disappeared as a matter of course. Once some priests begin preaching that the Bible supports social justice, even the Church is repressed, a shocking maneuver in such a heavily Catholic country. Into that vacuum then flow a number of conservative evangelical sects, whose profit-positive and more self-centered theology are a much better fit for the military-business oligarchy.

That same oligarchy thinks nothing of sending its soldiers—sometimes flying American helicopters and often fresh from being trained by American Special Forces—into the mountains to threaten and sometimes massacre opponents. In one scene, soldiers stride into a village, bellowing that everybody has 10 minutes to gather. The speed with which everybody comes running says volumes about how they understand the costs of not complying: “Blood bath” is how one interviewee puts it.

In the main, When the Mountains Tremble is an impressive example of a highly idealistic nonfiction film. Such extraordinary access to so many sources, however, is also a thing of the past. At the time, the Guatemalan ruling classes was living in such a bubble of unquestioned and self-unreflective power that they didn’t feel the need to censor themselves, just as the American trainers didn’t feel the need to hide their faces when the cameras appeared. After all, they were fighting Communism, so what did they need to ashamed of?